1). Field of the Invention
This invention relates to the generation of ionizing radiation, such as x-ray, gamma rays, and ultraviolet light. The invention particularly relates to an anode assembly for generating such ionizing radiation and to instruments incorporating such an anode assembly.
2). Discussion of Related Art
A variety of electron microscopes and surface analyzers have evolved recently. One approach to chemometric surface analysis is electron spectroscopy for chemical analysis (ESCA), also known as x-ray photoelectron spectrometry (XPS). Instruments, such as XPS, involve irradiating a sample surface with x-rays and detecting the photoelectrons emitted, which are characteristic of the chemical elements in the surface of the sample. Impinging accelerated electrons onto the surface of an anode is a means of generating such x-rays for such an XPS instrument.
It is desirable to generate an intense x-ray beam for use in an instrument, such as an XPS, to provide better sample throughput and signal processing. Greater x-ray beam intensities generate greater heating of the anode. Recent developments in anode design and structure to better dissipate and remove heat from the anode is disclosed in U.S. Pat. No. 5,315,113 (Larson).
Larson discloses a metal anode mounted on a highly conductive diamond member, with a support block having a channel therein receptive of a fluid coolant. Under the conditions of intense heating and bombardment by energetic electrons, the metal anode often degrades quickly and often delaminates from the diamond member. There is a need to provide an anode having a metal anode strongly bonded to the diamond member, so that the anode structure can withstand higher beam intensities and energies. Anodes typically have very short lifetimes within such instruments, thus it would be desirable to provide a more robust anode with a longer lifetime.